The invention relates to pyrotechnic caps and particularly to hermetically-sealed pyrotechnic caps capable of being activated by radiant energy in the form of light and/or heat.
In the aforementioned U.S. Pat. No. 4,130,082, there is described a unique concept in the production of substantially simultaneous high intensity audible and visual signals. As described therein it has been discovered that hermetically sealed plastic caps having a pyrotechnic composition therein can be instantaneously and reliably activated by the highly intense light from an adjacent chemical flashlamp to produce an audible signal also of high intensity (e.g. approaching 165 decibels). By chemical flashlamp is meant one having a light-transmitting (e.g. glass) envelope which includes a combustion-supporting atmosphere and a quantity of combustible material (e.g. zirconium) therein. The preferred activating flashlamps are those presently utilized in the photoflash product manufactured and sold by the assignee of the instant invention under the name "MAGICUBE". As described in U.S. Pat. No. 4,130,082, it is also possible to activate the sealed caps using other varieties of flashlamps such as those which are electrically activated. One example of this latter type are the flashlamps currently utilized in the photoflash product manufactured and sold by the assignee of the instant invention under the name "FLIPFLASH". A primary use for the above device is as an intrusion alarm. The device may also comprise part of an alarm system wherein a suitable detector is used to receive the device's output and thereafter perform an auxiliary function (e.g. emit a prolonged, high intensity signal).
A well-known characteristic of pyrotechnic compositions is that such materials are readily capable of being mechanically activated (e.g. by impact or crushing). In fact, many manufacturers have taken steps to increase the mechanical sensitivity of their compositions in view of the intended use of such products. For example, toy cap manufacturers have added quantities of sand to their compositions to reduce the impact necessary to provide cap ignition. The hard, abrasive sand serves to grind the mixture during said impact. In similar fashion, the producers of pyrotechnic compositions for such use as primers in percussively-actuated flashlamps have added metal particles to their compositions.
As described above, it has been found that many pyrotechnic compositions, when hermetically sealed in a suitable container and located near a flashlamp, can be successfully ignited by the radiant energy from said flashlamp. When used in this manner, it is understood that mechanical activation is not necessary for ignition of the respective cap members. It is also readily understood that in many instances (e.g. shipping, storage, etc.), it is highly desirable to reduce the mechanical sensitivity of such products. Heretofore, methods of accomplishing such a feat have been nonexistent.
It is believed, therefore, that a cap member having a pyrotechnic composition capable of being readily ignited by radiant energy from a flashlamp and also substantially desensitized to mechanical actuation in comparison to pyrotechnic products of the prior art would constitute a significant advancement in this art.